Method for adjusting the web tension of a processing machine

ABSTRACT

For adjusting the web tension of a processing machine for processing a continuous material, in particular a shaftless printing press, the continuous material is subdivided into at least two web-tension sections, with one web-tension section being limited by two clamping points; the web tension is adjusted in the at least two web-tension sections when the continuous material comes to a standstill.

CROSS-REFERENCE TO A RELATED APPLICATION

The invention described and claimed hereinbelow is also described inGerman Patent Application DE 10 2007 053 527.0 filed on Nov. 9, 2007.This German Patent Application, whose subject matter is incorporatedhere by reference, provides the basis for a claim of priority ofinvention under 35 U.S.C. 119(a)-(d).

BACKGROUND OF THE INVENTION

The present invention relates to a method for adjusting the web tensionof a processing machine, an appropriate computer program, and anappropriate computer program product.

Although the text below refers mainly to printing presses, the presentinvention is not limited thereto, but rather is directed to all types ofprocessing machines with which a continuous material and/or a materialweb is processed. The present invention may be used, in particular, withprinting presses such as newspaper presses, jobbing presses, gravurepresses, printing presses for packaging or currency, and processingmachines such as bagging machines, envelope machines, or packagingmachines. The continuous material may be paper, cardboard, plastic,metal, rubber, or foil, etc.

With processing machines, in particular printing presses, a continuousmaterial is moved along by driven axles (web conveyance axles), such astension rollers or feed rollers, and by non-driven axles, such asbreaker rollers, guide rollers, drying rollers, or cooling rollers. Thecontinuous material is simultaneously processed—e.g., printed on,punched, cut, folded, etc.—using processing axles, which are usuallyalso driven.

The web tension of the continuous material is influenced via “clampingpoints”, which clamp the continuous material in a frictional, form-fit,or non-positive manner. Driven conveyance or processing units aretypically involved. With a gravure press, a clamping point is typicallyformed by a printing unit, with which a frictional unit exists betweenthe driven impression cylinder, the pressure roller, and the materialweb. The continuous material is subdividable into web-tension sections,with a web-tension section being limited by two clamping points. Furtherdriven and/or non-driven axles may be located within a web-tensionsection. It is often possible to subdivide the entire web of continuousmaterial into several web-tension sections, with also have differentweb-tension setpoint values.

After processing has started, the web tension changes in the individualweb-tension sections until a static web-tension behavior sets in themachine after a certain period of time, i.e., until the web tension inthe individual web-tension sections reaches a static value. Thisadjustment and/or “back and forth” process requires a certain amount oftime, during which the processing machine mainly generates waste. Theprocessing machine is unable to produce products of adequate qualityuntil a static state has been reached.

DE 10 2006 004 307 A1 discloses a method that may shorten the timerequired for the start-up process. The action that is described involvesequipping the individual web-tension sections with web-tension measuringdevices and adjusting the web tension while the machine is running. Thedisadvantage of the method is that a certain amount of waste is stillproduced, and it is a complex procedure to adjust the web tension duringprocessing, since, in particular, the angular position of the printingunits must be taken into account in order to ensure that register ismaintained.

SUMMARY OF THE INVENTION

The present invention is therefore based on the object of providing animproved method for adjusting the web tension, with which a stationarymachine state may be attained more quickly and waste is reduced.

This object is attained via a new method for adjusting web tension, acomputer program, and a computer program product having the features ofthe present invention. Advantageous refinements are the subject of thedescription below.

With the method according to the present invention for adjusting the webtension of a processing machine, in particular a shaftless printingpress—the continuous material being subdividable into at least twoweb-tension sections, and one web-tension section being limited by twoclamping points—the web tension is adjusted in the at least twoweb-tension sections when the continuous material comes to a standstill.

With the solution according to the present invention, it is possible toadjust the web-tension values—which become stable—as closely as possibleto the eventual end state, even before the machine run is started. As aresult, the period of time until a stationary machine state is reachedmay be shorted considerably, which results directly in a substantialreduction of waste. The values that set in when the machine is at astandstill may be determined, e.g., via formulations from previousproduction runs, via measuring the cylinder diameter and entering thediameter and/or setpoint web tensions, and/or via measurement runs withextrapolations or interpolations of the resultant web tensions.

With a preferred embodiment, the web tension in the web-tension sectionsis ascertained using measuring elements, preferably load cells, via thedriving torque of at least one of the clamping points that limits thisweb-tension section, and/or via operators (control engineering).

Advantageously, the web tension in a web-tension section is adjusted byacting upon or displacing at least one clamping point that limits thisweb-tension section.

Expediently, the web tension in a web-tension section is adjusted viaangular displacement, rate feedback, and/or limitation of the drivingtorque of at least one clamping point that limits this web-tensionsection.

Advantageously, the acting upon or adjustment of the at least oneclamping point that is used to adjust the web tension cascades tofurther clamping points. It is particularly advantageous to cascade theaction on the clamping point as a precontrol, and/or to cascade theassociated precontrol values to adjacent clamping points, in order todecouple the adjacent web-tension sections from the affected web-tensionsection. The cascading may be carried out with different factors, e.g.,inverse, proportional, percent, etc.

According to a preferred embodiment, the web tension in the at least twoweb-tension sections is adjusted in succession, following the course ofthe continuous material. The adjustment may follow the course of thecontinuous material starting with an infeed and ending with an outfeed,with the web tension being adjusted in the consecutive web-tensionsections in succession. The adjustment may take place starting with theoutfeed and ending with the infeed. With this method, the web tension inthe entire machine may be adjusted quickly and easily.

Even though a preferred embodiment is described below with which theadjustment takes place from the infeed to the outfeed, following thecourse of the continuous material, it is understood that the methoddescribed may also be used to adjust the web tension against the courseof the continuous material, from the outfeed to the infeed.

Expediently, to perform the inventive method, the continuous material isinitially clamped via a first clamping point and a second clampingpoint. These may be, in particular, an infeed and an outfeed of theprocessing machine. Next, the web tension in the web-tension sectionbetween the first clamping point and the second clamping point isadjusted. The adjustment may preferably take place by rotating theinfeed and/or the outfeed. Expediently, the web-tension value that willset in essentially corresponds to the value—that sets in—of the webtension between the infeed and the first printing unit after it, or, ingeneral, between the first clamping point and the next clamping pointalong the course of the continuous material, which is referred to hereas the third clamping point. The continuous material is then clamped viathe third clamping point; the third clamping point along the course ofthe continuous material lies between the first clamping point and thesecond clamping point. Next, the second clamping point may be used toadjust the web tension along the course of the web tension between thethird clamping point and the second clamping point. With this method,the web tension in at least two web-tension sections may be adjustedquickly and easily.

It is advantageous when a change in web tension—which results from theeventual clamping of the continuous material with the third clampingpoint—is taken into account when the web tension is adjusted in theweb-tension section between the first clamping point and the secondclamping point. Clamping the continuous material via a clamping pointusually results in the continuous material becoming wrapped around therollers, i.e., the distance covered by the material web changes, andusually becomes longer. This results in an increase in web tension. Whenthis change in web tension is taken into consideration before theweb-tension values stabilize, the intended web-tension value in therelated web-tension section may be attained via the eventual clampingand resultant change in web tension.

The adjustment method described above may be expediently expanded byadjusting the web tension in the web-tension section between the firstclamping point and the second clamping point. The continuous material isthen clamped with a fourth clamping point, which is located between thefirst clamping point and the third clamping point along the course ofthe continuous material. It is understood that, with the refinementdescribed above as well, the change in web tension induced by thesubsequent clamping should be taken into account in the adjustment. Withthis method, the web tension in at least one further web-tension sectionmay be adjusted quickly and easily.

The adjustment method described above may be expediently expanded bysubsequently releasing the continuous material from the third clampingpoint and then clamping it at a fifth clamping point, which is locatedbetween the third clamping point and the second clamping point along thecourse of the continuous material. The web tension in the web-tensionsection between the fourth clamping point and the fifth clamping pointis then adjusted. Finally, the continuous material is clamped with thethird clamping point once more.

Finally, it is expedient to adjust the web tension in the web-tensionsection between the fifth clamping point and the second clamping point.

In combination with the method steps described in the paragraphs above,depending on the embodiment of the processing machine, it is possible toattain an adjustment of different web-tension values in at least fourweb-tension sections without the need to move the continuous material,which would result in waste. It is understood that the method stepsdescribed above may be combined and repeated in any order. The number ofweb-tension sections to be adjusted is therefore not limited with themethod according to the present invention.

The method according to the present invention may be used particularlyadvantageously with a processing machine that is designed as a printingpress, the clamping points being designed as an infeed, outfeed, and/orprinting units.

Expediently, the web tension is adjusted in a web-tension section viathe angular displacement of a clamping point that limits thisweb-tension section, the change in web tension in this web-tensionsection induced by this angular displacement is ascertained, and, basedthereon, a physical property of the continuous material (101), inparticular the elasticity module, is ascertained. It is thereforepossible—in a particularly easy manner—to ascertain additional physicalproperties that are helpful for the operation of a printing press.

An inventive processing machine includes, in particular, all means forcarrying out an inventive method.

The present invention also relates to a computer program with programcode means for controlling a processing machine according to the presentinvention when the computer program is run on a computer or anappropriate arithmetic unit, in particular in a processing machineaccording to the present invention.

The computer program product—which is provided according to the presentinvention—with program code means, which are stored on acomputer-readable data storage device, is designed to control—accordingto the present invention—a processing machine when the computer programis run on a computer or an appropriate arithmetic unit, in particular ina processing machine. Suitable data storage devices are, in particular,diskettes, hard drives, Flash drives, EEPROMs, CD-ROMs, DVDs, etc. It isalso possible that a program could be downloaded from computer networks(Internet, intranet, etc.).

The novel features which are considered as characteristic for thepresent invention are set forth in particular in the appended claims.The invention itself, however, both as to its construction and itsmethod of operation, together with additional objects and advantagesthereof, will be best understood from the following description ofspecific embodiments when read in connection with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic depiction of a processing machine designed as aprinting press, based on which a preferred embodiment of the methodaccording to the present invention is described.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A processing machine designed as a printing press is labeled as a wholewith reference numeral 100 in FIG. 1. A material to be printed on, e.g.,paper 101, is supplied to the machine via an infeed 110. Paper 101 isthen guided through clamping points, which are designed as printingunits 111, 112, 113, 114, and they are printed on, then output via anoutfeed 115. The infeed, outfeed, and printing units 110 through 115 arelocated such that they may be positioned, in particular such that theircylinders or angles may be corrected. Printing units 111 through 114 arelocated in a web tension-controlled region between infeed 110 andoutfeed 115.

Printing units 111 through 114 each include an impression cylinder 111′through 114′, against each of which a pressure roller 111″ through 114″is pressed with strong pressure. Impression cylinders 111′ through 114′may be driven separately and independently of one another. Associateddrives 111′″ through 114′″ are depicted schematically. Pressure rollers111′″ through 114′″ are designed such that they may rotate freely.Infeed 110 and outfeed 115 each include two cylinders, which rotate inopposite directions and guide paper 101. Infeed 110 and outfeed 115 mayalso be driven separately by a drive 110′″ and 115′″. Infeed 110 andoutfeed 115 and printing units 111 through 114 form—with paper 101passing through them—one unit that is connected via a frictionconnection. Infeed 110, outfeed 115, and printing units 111 through 114therefore each represent one clamping point.

In the web sections (web-tension sections) between individual printingunits 111 through 114, paper 101 is initially guided via a few rollers,which are labeled 102 and are not explained in greater detail. Forclarity, not every roller is labeled with reference numeral 102. Therollers may be, in particular, deflection rollers, drying rollers,cooling rollers, cutting devices, etc. In addition, detection devicesfor determining the web tension are provided in the web-tensionsections. An arithmetic unit 200 is provided to control the printingpress and to adjust the web tension.

The text below describes how, with the embodiment of the printing presspresented here, the web tension is adjusted—starting with infeed 110 andending with outfeed 115—according to a preferred embodiment of thepresent invention when the continuous material comes to a standstill.

Sensors (not depicted)—which determine the web tension of continuousmaterial 101, and, for this purpose, are designed as load cells—arelocated in the individual web-tension sections between clamping points110 through 115. The web-tension values to be adjusted may be determinedin advance using a measurement run.

Starting at the state shown, when continuous material 101 is at astandstill, pressure rollers 111″ through 114″ are halted, i.e.,continuous material 101 is released from clamping points 111 through114, which are designed as printing units. The web tension in the entiremachine is then set to a first basic value by infeed 110 and/or outfeed115.

Pressure roller 112″ is then activated, i.e., the continuous material isclamped with printing unit 112. Via printing unit 112, the web tensionin the web-tension region between infeed 110 and printing unit 112 isadjusted such that it corresponds to a desired web tension in theweb-tension region between infeed 110 and first printing unit 111. Theincrease in web tension that eventually results via the clamping withprinting unit 111 is already taken into consideration in the adjustment.The web-tension sensors check the adjusted web tension. The check mayalso take place by evaluating the driving torque of printing unit 112 orvia observers that are commonplace in control engineering. Next,pressure roller 111″ of printing unit 111 is activated, and the processof adjusting the web tension in the web-tension region between infeed110 and first printing unit 111 is therefore completed.

Next, pressure roller 112″ of printing unit 112 is halted again, inorder to release continuous material 101 from printing unit 112.Pressure roller 113″ of printing unit 113 is then activated, in order toclamp the continuous material via printing unit 113. Using printing unit113, the web tension that is to eventually exist in the web-tensionsection between printing unit 111 and printing unit 112 is adjusted inthe web-tension section between printing unit 111 and printing unit 113,the change in web tension that results from the subsequent activation ofpressure roller 112″ being taken into account once more. Next, pressureroller 112″ is activated, and, with this, the adjustment procedure forthe web-tension section between printing unit 111 and printing unit 112is ended.

The adjustment of the web tensions in the web-tension sections betweenprinting units 112 and 113, and between 113 and 114 is carried out inthe same manner. The desired web tension in the web-tension sectionbetween printing unit 113 and printing unit 114 is attained bydisplacing outfeed 115. After pressure roller 114″ is activated, i.e.,after continuous material 101 is clamped with printing unit 114, the webtension in the last web-tension section between printing unit 114 andoutfeed 115 is adjusted once more by adjusting outfeed 115.

It is understood that only one particularly preferred embodiment of thepresent invention is depicted in the figures shown. Any other type ofembodiment is also feasible, without leaving the framework of thepresent invention.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofmethods and constructions differing from the types described above.

While the invention has been illustrated and described as embodied in amethod for adjusting the web tension of a processing machine, it is notintended to be limited to the details shown, since various modificationsand structural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

1. A method of adjusting a web tension of a processing machine forprocessing a continuous material, comprising the steps of subdividingthe continuous material into at least two web-tension sections; limitingone of the web-tension sections by two clamping points; and adjusting aweb tension in the at least two web-tension sections when the continuousmaterial comes to a standstill, further comprising ascertaining the webtension in the web-tension sections using measuring elements via adriving torque of at least one of the clamping points that limits theweb-tension section, and/or via operators.
 2. A method as defined inclaim 1, wherein the method for adjusting the web tension of aprocessing machine for processing a continuous material is a method foradjusting the web tension of a processing machine which is a shaftlessprinting press.
 3. A method as defined in claim 1, further comprisingascertaining the web tension in the web-tension sections using measuringelements via a driving torque of at least one of the clamping pointsthat limits the web-tension section, and/or via operators.
 4. A methodas defined in claim 3, wherein said ascertaining the web tensionincludes using the measuring elements configured as load cells.
 5. Amethod as defined in claim 1, wherein said adjusting includes adjustingthe web tension in a web-tension section by acting on at least one ofthe clamping points that limits this web-tension section.
 6. A method asdefined in claim 1, said adjusting by acting on the at least oneclamping point includes adjusting the web tension in the web-tensionsection via angular displacement, rate feedback, and/or limitation of adriving torque of the at least one clamping point that limits theweb-tension section.
 7. A method as defined in claim 1, furthercomprising cascading an action applied to at least one of the clampingpoints to further clamping points.
 8. A method as defined in claim 1,wherein said adjusting of the web tension in the at least twoweb-tension sections includes adjusting in succession, following acourse of the continuous material.
 9. A method as defined in claim 1,further comprising clamping the continuous material at a first clampingpoint and a second clamping point, adjusting the web tension in aweb-tension section between the first clamping point and the secondclamping point, clamping the continuous material with a third clampingpoint located between the first clamping point and the second clampingpoint along a course of the continuous material.
 10. A method as definedin claim 9, further comprising taking into consideration a change in theweb tension when the continuous material is clamped via the thirdclamping point when the web tension is adjusted in the web-tensionsection between the first clamping point and the second clamping point.11. A method as defined in claim 9, further comprising adjusting the webtension in a web-tension section between a first clamping point and thethird clamping point, clamping the continuous material at a fourthclamping point located between the first clamping point and the thirdclamping point along the course of the continuous material.
 12. A methodas defined in claim 11, further comprising releasing the continuousmaterial from the third clamping point, clamping the continuous materialat a fifth clamping point located between the third clamping point andthe second clamping point along the course of continuous material,adjusting the web tension in a web-tension section between the fourthclamping point and the fifth clamping point, and clamping the continuousmaterial at the third clamping point.
 13. A method as defined in claim12, further comprising adjusting the web tension in a web-tensionsection between the fifth clamping point and the second clamping point.14. A method as defined in claim 1, wherein the method for adjusting theweb tension of a processing machine is performed in the processingmachine configured as a printing press, and further comprisingconfiguring the clamping points as printing units selected from thegroup consisting of an infeed printing unit, an outfeed printing unit,and other printing units.
 15. A method as defined in claim 1, whereinsaid adjusting includes adjusting in a web-tension section via anangular displacement of one of the clamping points that limits thisweb-tension section, ascertaining a change in web tension in thisweb-tension section induced by the angular displacement, and, basedthereon, ascertaining a physical property of the continuous material.16. A method as defined in claim 15, wherein said ascertaining includesascertaining an elasticity module of the continuous material.
 17. Acomputer program with program code means for carrying out the methodrecited in claim 1 when the computer program is run on a device selectedfrom the group consisting of a computer and an appropriate arithmeticunit.
 18. A computer program product with program code means stored on acomputer-readable data storage device for carrying out the methoddefined in claim 1 when the computer program is run on the deviceselected from the group consisting of a computer and an appropriatearithmetic unit.